CN107879366B

CN107879366B - Activation method for extracting aluminum oxide from fly ash

Info

Publication number: CN107879366B
Application number: CN201711043300.8A
Authority: CN
Inventors: 郁青春; 叶标; 杨斌; 邓勇; 陈秀敏; 王飞; 徐宝强; 刘大春; 蒋文龙; 李一夫
Original assignee: Kunming University of Science and Technology
Current assignee: Kunming University of Science and Technology
Priority date: 2017-10-31
Filing date: 2017-10-31
Publication date: 2020-02-07
Anticipated expiration: 2037-10-31
Also published as: CN107879366A

Abstract

The invention relates to an activation method for extracting aluminum oxide from fly ash, belonging to the technical field of aluminum oxide. Firstly, after ball milling, respectively passing the fly ash and the roasting activator through a 120-mesh standard sieve, uniformly mixing the fly ash and the roasting activator according to the mass ratio of 1: 0.5-4.0, and then roasting the mixture for 0.5-2 hours at the temperature of 750-950 ℃ to obtain a roasted material; wherein the roasting activator is a mixed roasting activator of sodium carbonate or sodium chloride and calcium chloride; adding 1-3 mol/L sulfuric acid solution into the obtained roasted material according to the liquid-solid ratio of 8-15: 1mL/g, leaching for 1-2 h at the temperature of 70-90 ℃, and performing solid-liquid separation to obtain aluminum sulfate solution and tailings. The method has the effects of low energy consumption, low cost and high extraction rate, and opens up a new method for the high value-added utilization of the fly ash.

Description

Activation method for extracting aluminum oxide from fly ash

Technical Field

The invention relates to an activation method for extracting aluminum oxide from fly ash, belonging to the technical field of aluminum oxide.

Background

Fly ash is a solid waste discharged from coal-fired power plants. A large amount of fly ash is generated in China every year, but the utilization rate is low, and the fly ash is mainly used in extensive scale utilization, such as road engineering, backfill engineering and building engineering. The chemical components of the fly ash are mainly alumina and silicon dioxide, and a small amount of ferric oxide and other scattered metals are also contained. The extensive utilization not only brings huge pressure to the environment, but also wastes valuable components in the fly ash. This is inconsistent with the direction of building resource-saving and environment-friendly society, so that now the comprehensive utilization of fly ash is more and more important, and the fly ash is used to extract alumina, silica and rare metals to synthesize composite materials such as zeolite materials and mullite. The extraction of alumina from the fly ash is beneficial to the comprehensive utilization of the fly ash, and has good social and economic benefits.

The alumina in the fly ash is mainly in mullite, the mullite is stable in property and difficult to dissolve in acid and alkali, and is difficult to directly utilize without treatment. The fly ash is activated to destroy Al-Si bonds in the mullite, so that the activity of alumina in the fly ash is improved, and the decomposition of the mullite and the extraction of the alumina are facilitated. At present, a plurality of methods for activating and treating the fly ash are mainly mechanical activation, roasting activation, acid leaching activation, microwave activation and the like.

The mechanical activation can reduce the granularity of the fly ash and increase the surface area of the solid, thereby improving the chemical activity of the fly ash. The influence of an activation mode on alumina dissolution in fly ash sintered clinker by Tang cloud and the like light metal 2009(4) 19-21. experimental research shows that: by controlling other experimental conditions, the dissolution rate of alumina increases and then decreases as the degree of mechanical activation increases, and the dissolution rate of alumina increases to 80.82% after the mechanical activation step is added.

Roasting activation is the most studied and mature activation mode of the process at present. The roasting activator mainly comprises limestone, soda lime, sulfate and the like. Zhaji et al, research on extraction of alumina from fly ash by limestone sintering method, metal materials and metallurgical engineering, 2008, 36(2):16-18. experiments on extraction of alumina from fly ash by limestone sintering method were carried out, and the dissolution rate of alumina was more than 79% under the conditions that the raw material formula C/A value was 1.8, the roasting temperature was 1380 ℃, and the holding time was 60 min. Schrucjin root, et al, research on extraction of alumina from fly ash by soda lime sintering method, comprehensive utilization of fly ash, 1992(1), 20-23, research on extraction of alumina from fly ash by soda lime sintering method was carried out, when desiliconized fly ash was used as raw material, calcium ratio was 2.1, alkali ratio was 0.96, and calcination was carried out at 1220 deg.C for 30min, the standard dissolution rate of alumina was more than 94%. Li Lai Shi et al, chemical bulletin of "preparation of high purity alumina from fly ash", 2006, 57(9): 2189-.

Acid leaching activation is the mode with the highest activation efficiency at present. Mainly comprises a hydrochloric acid leaching method, a concentrated sulfuric acid leaching method and an ammonium fluoride dissolution assisting method. "preparation and application of polymeric aluminum", university of Liaoning engineering, 2009,28(s2): 100-: calcining the fly ash at 700 ℃, and leaching the fly ash for 3 hours at 90 ℃ by using 17% hydrochloric acid, wherein the volume mass ratio of the hydrochloric acid to the fly ash is 4 ml/g, and the leaching rate of aluminum can reach 35%. The Chenchao rank et al, namely 'directly leaching alumina from fly ash by using sulfuric acid', hydrometallurgy, 2013(5):309 and 311. through experimental research, the leaching time of the fly ash in sulfuric acid with the initial concentration of 3.7mol/L and the temperature of 180 ℃ is 5h at the liquid-solid ratio of 5:1, and the leaching rate of alumina is 94.16%. Zhao Jianyu, et al, research on a novel process for extracting alumina from fly ash by using an ammonium fluoride dissolution assisting method, inorganic salt industry 2003, 35(4):40-41. the extraction rate of alumina in fly ash can reach more than 97% by using the ammonium fluoride dissolution assisting method.

The microwave radiation can quickly raise the temperature of the reaction system, promote the breakage of Al-Si bonds and reduce the activation energy of the reaction. Inorganic salt industry 2005, 37(2):47-49. high temperature sintering-microwave radiation combined operation process is adopted, radiation is carried out for 2-3min under the condition that the primary microwave radiation power is 450W, radiation is carried out for 8-10min under the condition that the secondary microwave radiation power is 720W, and the dissolution rate of alumina is more than 95%.

At present, the methods of the living methods are researched and have good experimental effects in laboratories, but the respective disadvantages also limit the industrial application of the methods to a great extent. The roasting agent for roasting activation is expensive, the extraction rate is not high, the energy consumption is large, the equipment requirement for acid leaching activation is high, the environmental pollution is large, the microwave activation has high extraction rate, but the heating technology is difficult to realize large-scale industrialization, and the comprehensive cost is high. Therefore, the method for extracting the alumina from the fly ash is low in energy consumption, low in cost and high in extraction rate and is very beneficial to find.

Disclosure of Invention

Aiming at the problems and the defects of the prior art, the invention provides an activation method for extracting alumina from fly ash. The method has the effects of low energy consumption, low cost and high extraction rate, and opens up a new method for the high value-added utilization of the fly ash. The invention is realized by the following technical scheme.

An activation method for extracting alumina from fly ash comprises the following specific steps:

step 1, firstly, screening the pulverized fuel ash and the roasting activator which are subjected to ball milling respectively through a 120-mesh standard sieve, uniformly mixing according to the mass ratio of 1: 0.5-4.0, and roasting at the temperature of 750-950 ℃ for 0.5-2 h to obtain a roasted material; wherein the roasting activator is a mixed roasting activator of sodium carbonate or sodium chloride and calcium chloride;

and 2, adding a 1-3 mol/L sulfuric acid solution into the roasted material obtained in the step 1 according to a liquid-solid ratio of 8-15: 1mL/g, leaching for 1-2 h at the temperature of 70-90 ℃, and performing solid-liquid separation to obtain an aluminum sulfate solution and tailings.

The mass ratio of the sodium carbonate or the sodium salt of the sodium chloride to the calcium chloride is 1: 1.0-1: 9.0.

The invention has the beneficial effects that:

(1) the invention uses the advantages of composite roasting activator, sodium carbonate or sodium chloride sodium salt activator, such as low price and CaCl₂The aluminum extraction rate of the activating agent is high.

(2) Compared with a limestone sintering method (1300-.

(3) The invention has no requirement on the content of alumina in the fly ash, and is also suitable for the low-alumina fly ash which is not pretreated and desilicated.

Detailed Description

The present invention will be further described with reference to the following embodiments.

The fly ash of all examples of the invention is from a thermal power plant in Henan, and the chemical composition of the fly ash is shown in Table I.

TABLE 1 chemical composition of fly ash (% by mass)

Al₂O₃	SiO₂	TFe	CaO	MgO	Loss on ignition
						24.48	53.38	3.57	1.64	0.74	7.24

Example 1

The activation method for extracting alumina from fly ash comprises the following specific steps:

step 1, firstly, screening the pulverized fuel ash (the percentage content of the pulverized fuel ash is shown in table 1) and the roasting activator which are respectively subjected to ball milling through a 120-mesh standard sieve, uniformly mixing according to the mass ratio of 1:4.0, and then roasting for 1.33h at the temperature of 850 ℃ to obtain a roasted material; wherein the roasting activator is a mixed roasting activator of sodium carbonate and calcium chloride; the mass ratio of the sodium carbonate to the calcium chloride is 1: 4.0;

and 2, adding the roasted material obtained in the step 1 into a sulfuric acid solution with the concentration of 1mol/L according to the liquid-solid ratio of 8:1mL/g, leaching for 1h at the temperature of 70 ℃, and performing solid-liquid separation to obtain an aluminum sulfate solution and tailings.

After the embodiment, the content of alumina and silica in the tailings is detected, and the extraction rate of alumina is calculated to be 91.83%. Compared with the pure calcium chloride activator, the cost is reduced by 1425 yuan/ton, and the extraction rate is not much different from the extraction rate of 91.24% of the calcium chloride activator.

Example 2

step 1, firstly, uniformly mixing pulverized fuel ash (the percentage content of the pulverized fuel ash is shown in table 1) and roasting activator which are respectively subjected to ball milling with a 120-mesh standard sieve according to a mass ratio of 1:0.5, and then roasting for 2 hours at the temperature of 750 ℃ to obtain a roasted material; wherein the roasting activator is a mixed roasting activator of sodium carbonate and calcium chloride; the mass ratio of the sodium carbonate to the calcium chloride is 1: 1;

and 2, adding the roasted material obtained in the step 1 into a sulfuric acid solution with the concentration of 3mol/L according to the liquid-solid ratio of 15:1mL/g, leaching for 2 hours at the temperature of 90 ℃, and performing solid-liquid separation to obtain an aluminum sulfate solution and tailings.

After the embodiment, the content of alumina and silica in the tailings is detected, and the extraction rate of alumina is calculated to be 88.45%. Compared with the method which only adopts the calcium chloride activator, the cost is reduced by 462 yuan/ton, and compared with the extraction rate which only adopts the calcium chloride activator and is 87.8 percent, the extraction rate is not much different.

Example 3

step 1, firstly, uniformly mixing pulverized fuel ash (the percentage content of the pulverized fuel ash is shown in table 1) and roasting activator which are respectively subjected to ball milling with a 120-mesh standard sieve according to a mass ratio of 1:2.0, and then roasting at 950 ℃ for 0.5h to obtain a roasted material; wherein the roasting activator is a mixed roasting activator of sodium chloride and calcium chloride; the mass ratio of the sodium chloride to the calcium chloride is 1: 9.0;

and 2, adding the roasted material obtained in the step 1 into a sulfuric acid solution with the concentration of 2mol/L according to the liquid-solid ratio of 10:1mL/g, leaching for 1.5h at the temperature of 80 ℃, and performing solid-liquid separation to obtain an aluminum sulfate solution and tailings.

After the embodiment, the content of alumina and silica in the tailings is detected, and the extraction rate of alumina is calculated to be 94.12%. Compared with the pure calcium chloride activator, the cost is reduced by 1128 yuan/ton, and compared with the extraction rate of 93.56% of the calcium chloride activator, the extraction rate is not much different.

While the present invention has been described in detail with reference to the specific embodiments thereof, the present invention is not limited to the embodiments described above, and various changes can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art.

Claims

1. An activation method for extracting alumina from fly ash is characterized by comprising the following specific steps:

step 1, firstly, screening the pulverized fuel ash and the roasting activator which are subjected to ball milling respectively through a 120-mesh standard sieve, uniformly mixing the pulverized fuel ash and the roasting activator according to the mass ratio of 1: 0.5-4.0, and roasting the mixture for 0.5-2 hours at the temperature of 750-950 ℃ to obtain a roasted material; wherein the roasting activator is a mixed roasting activator of sodium carbonate and calcium chloride or sodium chloride and calcium chloride;

step 2, adding a 1-3 mol/L sulfuric acid solution into the roasted material obtained in the step 1 according to a liquid-solid ratio of 8-15: 1mL/g, leaching for 1-2 h at the temperature of 70-90 ℃, and performing solid-liquid separation to obtain an aluminum sulfate solution and tailings;